US3699014A - Vibratory process - Google Patents

Abstract

A PROCESS AND APPARATUS FOR ELECTRODEPOSITION UTILIZING A LIQUID ELECTROLYTE WHEREIN A VERY HIGH SOLID TO LIQUID VOLUMETRIC RATIO OF SMALL DYNAMICALLY HARD PARTICLES IS INCORPORATED IN THE SYSTEM AND SUCH PARTICLES ARE MAINTAINED IN A VIBRATORY CONTACT WITH ALL SURFACES OF THE ARTICLE BEING PLATED THROUGHOUT THE PERIOD OF PLATING.

Description

Oct 17, 1972 s, ElsNER 3,699,014

vIBhAToRY PROCESS Filed Dec. 29, 1970 In vemfor Sfeve E/sner His Affarney.

United States Patent O 3,699,014 VIBRATORY PROCESS Steve Eisner, Schenectady, N.Y., assignor to Norton Company, Troy, N.Y. Filed Dec. 29, 1970, Ser. No. 102,287 Int. Cl. C23b 3/06 U.S. Cl. 204-35 R 3 Claims ABSTRACT OF THE DISCLOSURE A process and apparatus for electrodeposition utilizing a liquid electrolyte wherein a very high solid to liquid volumetric ratio of small dynamically hard particles is incorporated in the system and such particles are maintained in a vibratory contact with all surfaces of the article being plated throughout the period of plating.

FIELD OF THE INVENTION Electrodeposition of metal on another surface through electrochemical action has generally been a slow process. Particularly, this has been true in the production of dense, smooth, compact platings from aqueous solutions containing dissolved salts of the metal to be deposited. The present invention relates to this general field of electrodeposition.

RELATED APPLICATIONS The present application relates to a modification of the invention covered by my earlier filed copending application, Ser. No. 34,500, filed May 4, 1970 and entitled Electrodeposition, now U.S. Patent No. 3,619,384.

DESCRIPTION OF PRIOR ART Efforts have meen made in the past to mechanically improve electrodeposited metals. The use of small amounts of impact media such as glass spheres, sand and the like, has been tried with the idea that this would mechanically beat the plate deposited and make it more dense and coherent. Examples of this approach are illustrated in U .8. Letters Patent Nos. 712,153; 1,051,556 and 1,594,509. A much more recent approach directed to the improvement of deposition rates has been the mechanical activation described and claimed in my aforementioned copending application, Ser. No. 34,500. In that case it was found that by using a plurality of small, dynamically hard particles held in a fixed relationship to one another by a supporting media as a means of constantly activating or, if you will, irritating the surface being plated, plating speeds could be drastically increased. Further, by this mechanical activation it was found that plate of good brightness could be achieved without the necessity of chemical additives, although the process also operated well with such additives. One form of the activating device described in such earlier application was a plurality of small objects such as spheres or irregular shaped bodies made up of a ceramic or plastic matrix supporting many very small dynamically hard particles adhered to or protruding therefrom in spaced relationship to one another. Activating the surface as described in said application, Ser. No. 34,500, is described as so treating the surface "ice being plated as to create at such surface a high tendency to utilize the current to deposit the metal in sound, adherent form rather than as powder or dendrites. The dynamically hard particles used to accomplish this were defined as acting to produce such activation through a combination of the hardness of the particles, the contact pressure of the particles on the surface of the electrodeposit and the speed at which the particles move relative to the surface of the electrodeposit during plating.

SUMMARY The present invention involves the discovery that by causing a plurality of small, dynamically hard particles having a vibratory motion to completely surround or cover the surface to be plated throughout the plating cycle a unique speed-up in plating results so long as the ratio A of the volume of particles to liquid electrolyte is high.

The imparting of energy to this particular species of activating media through confinement of the media and the electrolyte within a vibrating housing or container, as contrasted to any other type of energy transmission, has been found essential to the satisfactory operation of this process. Plating rates were found to increase substantially as compared to rates achievable from the same baths in the absence of the activating particles.

DRAWINGS FIG. 1 is a schematic view of the preferred mode of operation of the process illustrating one type of equipment therefor.

FIG. 2 is a schematic illustration partially in section of a modification of the process and another type of equipment which may be used therefor.

DESCRIPTION OF PREFERRED EMBODIMENTS This process of the present invention requires the controlled application during plating of a plurality of small activating particles to the surface or surfaces being plated. Generally, these activating particles will be very small, i.e., having an average maximum dimension of up to about A" and preferably of about A" or less, in order to penetrate into small radius openings on the surface to be plated. The activating particles must be preferably non-conductive and insoluble in the electrolyte. For most metals a minimum dynamic particle hardness slightly greater than the hardness of the deposited metal is necessary but since higher hardnesses do not appear to produce adverse efiects, it is preferred, in order to avoid experimentation, to utilize particles having a hardness of about Knoop 500 or greater. The particles must be capable of being wet by the electrolyte with which they are used and should have a density greater than that of the electrolyte. An extremely wide variety of particulate materials may be used so long as they meet the above criteria. Suitable particles have been found to be glass, sand, abrasive grains (both natural and artificial), tumbling abrasives, ceramics and the like. These particles may be used alone or in blends of one or more kinds of particles with another kind, e.g., a particularly good blend, especially for nickel plating has been found to be a 60-40 mixture by volume of 30 mesh glass spheres and 30 mesh sintered bauxite particles.

While preferably the activating particles are all nonconductive in nature, it is possible to mix in some conductive particles if it is desired to decrease the electrical resistance between the anode and cathode. It has been found that up to about by volume of all conductive particles may be used with only slight hazard of forming a conductive path between the anode and cathode. Where the conductive particles are at least partially shielded by being provided with a non-conductive coating, greater percentages can be used.

The activating particles must be subjected to a vibratory action at all times during plating and the object or surface to be plated must be completely covered by these activating particles while plating is in progress. For decorative purposes, there frequently may be present a chemical additive of the various types known to the plating art. These additives are used in the amounts recommended by the manufacturer thereof for normal plating operations.

Typical additives which may be advantageously used in the present process are thiourea and its derivatives, e.g., ethyl thiourea; thiohydantoins, e.g., l-acetyl-Z-thiohydantoin; polyethers; e.g., Carbowax 6000, product of Union Carbide Corporation; organic polysulfide compounds such as those described in US. Pat. No. 3,328,273; aniline dyes, e.g., diethyl safranine azo dimethyl aniline and others described in US. Pat. No. 2,738,318; thiazine dyes, e.g., methylene green and others described in US. Pat. No. 2,805,193; colloidal materials such as glue or casein; thioaromatic compounds, e.g., diphenyl sulfide and others described in U.S. Pat. No. 2,424,887; chloride or bromide ions in various concentrations; ions of non-deposited metals, e. g., aluminum or magnesium in zinc plating baths or lead and selenium in cyanide copper baths; organic amines, e.g., tribenzylamine, tetraethylene pentamine; triethanolamine, etc.; hydrogen peroxide; aromatic polysulfonic acids, e.g., o-toluidine disulfonic acids; organic nitriles, e.g., as described in US. Pat. No. 2,524,010; carbonyl compounds, e.g., hydroxy-anthraquinone or conmarin, phenols, e.g., resorcinol; and combinations of the above.

In order to achieve proper coverage of the surfaces to be plated, an extremely high ratio of activating particles to electrolyte is required as is described in more detail below. Since the particles also have a density greater than that of the electrolyte it has been found that the only satisfactory means for imparting the required vibratory motion to such particles is by providing a container for the entire system and externally imposing a rapid vibratory motion to such container which in turn imparts the requisite motion to the particles by repeated impacts between the container walls and the enclosed particles. The motionso imparted is designed to give such particles a macroorbit or mass rotational movement of the particles within the container and hence past the part to be plated (maintained fixed with respect to the container. The macro-orbit of the particles is in a plane roughly parallel with a crosssection of the container taken normal to its longer axis. The motion also imparts micro-orbits to the particles which continue as the particles move in the macro-orbit, such micro-orbits varying depending upon the point of impact on the container wall which initiates the movement and upon impacts with other particles, but generally being quite small elliptical or circular paths. The part to be plated, as aforesaid, is maintained fixed in the sense that it is not free to be circulated in the macro-orbit of the particles. Means are provided to either fixture or anchor such part from the surface of the container or to mount such part completely independent of any contact by the mounting means with the container.

It is also necessary to provide proper electrical connections and supply meansto the workpiece to be plated and to the associated anodes. Preferably the anodes are aflixed to the mounting means for the workpiece although they can be independently mounted within the container if desired. The anode type, configuration and arrangement will depend upon the shape of the part to be plated. Generally, however, the anodes are preferably in the form of either thin rectangular bars or plates or in the form of rods of circular or elliptical cross-section so as to minimize interference with the macro-orbit of the activating particles. Because the anodes are also contacted by the activating particles, no problems of anode passivation are encountered and the process eliminates surface roughness on the electrodeposit which may occur in conventional plating through occlusion of small bits of anode material.

Since many plating baths require elevated temperatures, e.g., nickel plating baths, the preferred form of the apparatus of the present invention is as illustrated in FIG. 1 of the drawings (described in detail below). A heating means is provided surrounding the container within which the electrolyte-particle mass is contained. While shown in FIG. 1 as a jacket or chamber adapted to have a heating fluid circulated therethrough, obviously other means such as an electrical heating element encased in the container walls or positioned external of the container wall can be employed if desired. In small units, heating has been carried out by the use of heat lamps trained on the external surface of the vibrating container. Preferably, means are also provided to continuously or periodic-ally withdraw electrolyte from the system for filtration or other treatment and return of the treated electrolyte to the system.

Commercial vibratory abrasive finishing machines are available and can be readily modified in accordance with the present invention. Typical of such commercial units are the Rampe Model VOF-S 1, Vibrader and the Elliott Vibratub, Finisher Model 33.

A minimum vibration frequency of about 500 cycles per minute must be used in order to carry out this process. Vibration rates of 1,200 to 2,200 cycles per minute are preferred while greater rates may be used if desired. Amplitudes of vibration should range between about & inch and about /2 inch.

Plating rates will vary, depending chiefly upon the metal, being plated and upon the plating solution used, but will generally run from double up to 25 times greater than the maximum rate achievable from the same system without the activating particles present. For example, using a copper sulfate plating bath with a commercial brightener UBAC No. 1 (described in Bulletin CUP-UBAO- l 2M, November 1967 by The Udylite Corporation, Detroit, Mich. 48234), current densities (proportional to plating rates) as muchas 15 times greater than the recommended 60 amps/ft. were used with excellent results.

As indicated above, the process requires that the surface receiving the deposit be completely covered by the activating particles throughout the plating cycle. This differs from prior art efforts, where foreign objects were present in a plating or electrodeposition solution, in that the relative volume density of the activating particles to electrolye in the presen process is many times higher. The concentration of activating particles in the present process is sufficiently high that the part to be plated or to receive the electrodeposit could only with considerable difficulty be forced into the mass of activating particles to the desired depth absent the application of vibratory force to such mass. The depth of activating particles should generally be such (with the process stopped and no vibration being applied) as to exceed the height of the surface to be plated. The electrolyte level may either exceed or be lower than the level of the activating particles within the confines of the apparatus containing the combined fluid and media. As a practical consideration, keeping the activating particle level at or above the level of the electrolyte is frequently resorted to in order to minimize splashout of the fluid during vibration and is considered the preferred mode of operation. Alternatively, a suitable cover over the bath or floating of spheres or balls of insoluble plastic or the like on the surface of the electrolyte is utilized to contain such splash-out. Generally, the volumetric ratio of activating particles to fluid electrolyte in the plating zone (i.e., in the space within the plating container immediately surrounding or adjacent all of the surfaces to be plated), is not less than 1:1 when using normal, solid, geometrically shaped particles such as spheres, cylinders, cubes or irregular versions thereof. Of course, where the particles are made of highly porous materials, e.g., porous ceramics such as are used for catalyst supports, or have peculiar shapes such as a doughnut configuration, the desired coverage of the part to be plated may be achieved with a particle to liquid volumetric ratio of less than 1:1. However, the process requires the presence of a great number of these activating particles substantially encasing the part to be plated as contrasted with the suspension of a relatively few particles in the bath as has been done in the prior art. As a qualification applicable to any type of particle used, it is necessary that with the part in position and ready for plating, the number of particle in the plating zone does not differ by more than about 5% from such number when the system is in operation and plating is being carried out.

In operation, the small activating particles receive the vibratory motion described above by contact with the walls of the vibratory container which motion is then transferred from particle to particle within the container. The particles in the plating zone at any given time are both vibrating and also moving with respect to the part which is fixedly positioned in the container. It is estimated that each square inch area of the surface to be plated will be impacted repetitively about 500 to 150,000 times per second by these particles depending upon the frequency of vibration and the particle size. Essentially the particles, being of a very small size, form a complete layer over each surface to be plated but a layer which is moving laterally along or across each surface as well as vibrating normal thereto.

Referring now to the drawings, FIG. 1 schematically illustrates in partial cross-section a vibratory abrading machine adapted to carry out the present process. Reference numeral identifie the vibratory container or hopper mounted on dual drive shafts 11 which impart the vibration to container 10', A jacket 12 is provided on container 10 to permit heating the contents by passing steam through the jacket. Mounted inside container 10 is a cathode member 13 which is the part to be plated and associated anode members 14. The cathode 13' is supported from a cover plate 16 on top of container 10 by means of a support member 15. Likewise the anodes 14 are suspended from the cover member 16. Within the container 10 and completely covering the cathodic part 13 is a mass of small, hard non-conductive activating particles 17. The electrolyte level (shown at rest) 18 is below the top of the activating particles 17. In operation, the container 10 is set in vibration which in turn produces vibratory motion in the mass of particles 17 and electrolyte 18. The plating current is then turned on and the vibration continued throughout the plating cycle. A sump 19 is shown at the base of the container 10 to permit recirculation, make-up and filtration of the electrolyte if desired. The electrolyte is drawn off through outlet 0 and reintroduced through inlet I. A small mesh screen S over the sump prevents the small particles 17 from entering sump 19.

FIG. 2 schematically illustrates a typical vibrating tub machine used in the present process wherein a tub 20 (shown in partial cross-section) operatively connected to a drive motor 21 through shaft 22 is vibrated as shown by arrows A-A due to eccentric gearing in motor 21, counterweighted shafts or other devices known to the art to produce a vibratory motion as is commonly used in vibratory finishing operations. Contained within tank 20 is the electrolyte solution 23 and a plurality of activating particles 24. Completely immersed in the electrolyte 23 and having all of its surfaces to be plated below the level 25 of activating particles 24 is the workpiece 27. A suitable electrical connection 28 makes this workpiece 27 cathodic to the anodes 26 shown here as two spaced rods also extending down into the tub 20 and well below the surface of the electrolyte 23 and activating particle level 25. In operation, the tub 20 is set in vibration which in turn imparts vibration and movement to the activating particles 24 and electrolyte 23. The part 27 to be plated is inserted and thereafter the current is turned on and plating starts immediately. Vibration must be continued throughout the plating cycle and the plating current must be discontinued before the vibration is stopped or burning of the plate will occur at the relatively high current densities preferably employed. In most instances the plated workpiece 27 will be removed while the vibration is continued but after the plating current has been discontinued. It has been found desirable in some instances to impart independent vibration to the cathodic workpiece apart from the vibration imparted to the activating media. This has been done by mounting an auxiliary vibrator with a direct connection to the cathode support. Alternatively, the cathode support can be spring-mounted to the vibratory hopper containing the solution thereby imparting additional movement to the cathodic workpiece. However, as indicated above, the workpiece is not free to follow the macro-orbit of the particles in the container and is so positioned as to allow ample room on all sides to be plated for the passage of the activating particles. As discussed above, the electrolyte 23 may contain a chemical additive such as a brightening agent specific to the particular metal being plated out.

Example 1 Utilizing a commercial /3 cu. ft. vibratory abrasive finishing machine (Vibratube, Model 33), modified in accordance with the present invention to contain the anodes and cathodes as illustrated in FIG. 2 of the drawings, a brass plate approximately 2 x 4" was plated in a copper sulfate bath containing 300 parts Cu SO -5H and 1,000 parts water. The current density was held constant at 900 amps/ft. and plating was carried out for three minutes in each instance. Two runs were made with the vibration in each instance set at 2,100 cycles per minuate (and an amplitude of 5 Both runs were at room temperatures. In the first run, the bath was operated at the indicated conditions but without any activating particles present. In the second run activating particles were added to the same bath in the ratio of 3,000 parts plating solution to 6,000 parts activating objects by volume. These activating particles were irregular-shaped bodies of approximately 0.023 to 0.033 inch average diameter sintered bauxite tumbling abrasives designated as XM-30 and made as described in U.S. Patent No. 3,079,243.

Run 1 (bath alone)surface burned badly Run 2 (activating particles present)a sound dull copper deposit Example 2 Under the same conditions as above except for a reduction in the vibration rate from 2,100 cycles/minute to 1,200 cycles/minute, a repeat of the two runs gave these results:

Run 1 (bath alone)surface burned badly Run 2 (activating particles present)-a dull, smooth deposit obtained Example 3 Under the same conditions as in Example 1, the two runs were repeated, substituting as the activating objects polyester-bonded quartz, crushed and graded to pass through a U.S. 30-mesh screen and designated as D.30,

in the same volumetric ratio as used for XM-30" in EX- amples 1 and 2.

Run 1 (bath alone)-surface badly burned Run 2 (activating particles)a dull smooth deposit obtained Example 4 Under the same conditions as in Example 1, a chemical brightener UBAC No. l (The Udylite Corporation, Detroit, Mich.) was added to the bath in an amount of 0.5% by volume. When run with vibration but without the particles present the plate was extremely badly burned. With the particles used in Example 1 present in the amounts specified therein and vibration at 2100 cycles/minute the deposit was reflective and smooth and measurement of the surface before and after plating showed a 78% leveling to be obtained by plating under these conditions.

Example 5 Utilizing the modified vibratory apparatus of the previous examples, a pair of elliptical nickel anodes approximately 4%" long by 1%" wide and thick were positioned within the vibratory container. A cathode formed from a 9" x 1" strip of 0.025" thick mild steel having an initial surface finish of 6-7 microinches was positioned between the elliptical anodes, with the closest point of the cathode to anodes being 2". A plating solution formed from 40 oz./gal. NiSO -6H O, 8 oz./gal.

NiCl 61-1 and oz./gal. boric acid and 0.15 gram/liter coumarin additive was placed in the vibratory container so as to completely cover the cathodes and anodes. Electroplating was commenced (with the solution heated to 120-130 F.) without agitation and in the absence of any activating particles at a current density of 160 amps/ft. Severe burning of the surface occurred. The run was repeated, this time adding 6000 cc. of XM-30 particles per each 3000 cc. of plating solution. Vibration of the container at a frequency of 2100 cycles per minutes and an amplitude of was then instituted and the run carrier out for six minutes at a current density of 160 amps/ft A bright, adherent nickel deposit was obtained with a surface finish of 4-8 microinches.

Example 6 Under the same conditions as in Example 5, except that 0.2 gram/ liter saccharin was substituted for the coumarin additive, only burned plate was obtained without vibration and activating particles. With the same vibration and activating particles as in Example 5, a sound, bright nickel deposit having a surface finish of 3-6 microinches was achieved. A further run with the vibration only and omit ting the activating particles was found to give only a burned deposit.

Example 7 A Rampe Vi-Brader (R.T.M.) Model VOF-61 Vibratory Abrasive finishing apparatus was modified by providing a pair of supporting members afiixed to the top of the opening of the 5 cubic foot hopper of the unit. Suspended from each of these supporting members and rigidly connected thereto was a /2" diameter (circular crosssection) copper rod anode extending down into the vibratory hopper to within about 2" from the bottom of such hopper. A cross-bar was mounted between and anchored to each of the supporting members and depended therefrom at a distance of 3" from each of the anodes was a /2" diameter (circular cross-section) stainless steel rod of the same length as the anode rods adapted to serve as the cathode member. Electrical connections were made from the cathode and anodes to an external power source. A charge of 410 pounds of 30 mesh sintered bauxite particles (XM-30) and 5 gallons of a solution comprising 1000 parts water, 100 parts H 80 300 parts CuSO -5H O and 0.5 vol. percent of a commercial brightening agent (UBAC #1), was loaded into the 5 cubic foot vibratory hopper providing, with the unit at rest, a coverage of the electrodes by the particles for approximately 10 inches of their length and by the electrolyte for approximately 6 inches of their length. Vibration was applied to the hopper at a frequency of 1000 cycles per minute and an amplitude of 7 inch. Current flow was then initiated of 10 amps at 12 volts for 10 minutes. At the end of this time the current was stopped and the cathodic rod removed. The bottom 10" of the cathode was covered for 10" of its length with a bright, dense, coherent copper deposit. Since the cathode was stainless steel, it was possible to strip the deposit from the substrate for micrometer measurement of its thickness. An average thickness of 1.2 mils was measured which corresponds (for the 10 minute plating period) to a current density of amps per square foot. The removed plate was folded upon itself and showed good ductility.

Example 8 Using the same equipment set-up as in Example 7 and the same cathode-anode arrangement and particle-electrolyte charge as in Example 7, the vibration was stepped up to 2,200 cycles per minute with a /s" amplitude. This run was at an applied current of 35 amps at a voltage of 36 volts. The run was carried out for 5 minutes and the cathode then removed and the plate stripped therefrom. Again the plate was dense, coherent and ductile. The brightness was slightly less than in the preceding example but the measured thickness of the plate averaged 2.1 mils indicating an actual current density of 450 amps per square foot.

Example 9' Using the apparatus and electrode set-up described in Example 1, the vibratory container was filled to within about 2 inches of its capacity with an electrolyte solution comprising:

Grams/liter NaCl NiSO -6H O 134 H BO 32 Example 10 Example 9 was repeated-this time adding to the hopper 8,000 ml. of 30-mesh sintered bauxite particles (XM-30) along with 3,500 ml. of the plating solution. Plating was carried out at current densities ranging from 50 amperes per square foot to 85 amperes per square foot and a vibratory rate of 2,100 cycles per minute to produce bright, uniform nickel deposits with no evidence of burning as contrasted with the dark and burned samples of Example 9 at much lower current densities. A further run at 1,200 cycles/minute vibration and a current density of 73 amperes per square foot also produced a good bright nickel deposit.

Example 11 In order to evaluate different activating particles, a series of runs were made using the plating solution and apparatus set-up of Example 9. In all instances the activating particles were added in a volume ratio of 8,000 ml. per 3,500 ml. of plating solution. Vibration was provided at 2,100 cycles per minute.

Current density Type of activating particle Particle size (amps/ft?) Result Glass spheres 30 mesh 150 Bright deposit with a few scattered surface nodules. Garnet abrasive do 50 Setrni-Ih right deposit, no evidence of ur ng. Washed sea sand do 73 Semi-bright deposit, no burning. Crystalline AlzOUabresive graindo. 36 No burning and a semi-bright deposit. Zirconia-alumina abrasive do 50 Bright deposit, no sign of burning. Mixture of alumina balls (E-1-68, Nor- 5 parts ofamix- 150 Semi-bright plate with no burning.

ton 00.). ture 0124 to 40 mesh blended with 11 parts oi a mixture of 12 to 20 mesh. sintered bauxite.. 73 No burning and semi-bright deposit. 12 mesh 73 No burning and semi-bright deposit. 73 Semi-bright deposit with a few streaks where burning appeared to have occurred. Do by volume 100 Semi-bright deposit with no evidence 12 mesh and oi burning. 90% by volnine 30 mesh 25% washed sea sand and 75% glass 30 mesh each. 100 Bright deposit with no burning.

spheres (by volume). 75% washed sea send and 25% glass do 75 Do.

' spheres (by volume). 25% sintered bauxite (KM-30) and 75% do 100 Bright plate with no evidence of glass spheres (by volume).

Example 12 Using the apparatus and electrode set-up of Example 9, the plating bath was a standard Watts Nickel Bath. 8,000 ml. of activating particles per 3,500 ml. of plating solution were employed. The activating particles in this instance were composed of a blend of 25% irregular glass frit or granules (U.S. seive size 25-40) and 75% glass spheres (30 mesh). A bright deposit and no evidence of burning was achieved at a current density of 256 amps per square foot. The vibratory rate used was 2,100 cycles per minute.

Example 13 Using the apparatus and electrode set-up of Example 1 and the copper sulfate bath containing 0.5% by volume of UBAC #1 brightener described in Example 4 but with the cathode plate being a 2%" x 4" brass sheet bent into a concave shape over a 2" radius cylinder, plating was carried out using the activating particle type and volume ratio described in such Example 1. A bright, uniform, coherent copper deposit was formed on the contoured surface at a current density of 525 amperes per square foot.

Example 14 Following the conditions of Example 13 except using as the activating particles 30 mesh glass spheres, the current density was increased to a level of 1,800 amperes per square foot without causing burning of the deposit. The deposit was slightly duller than at the lower current densities but appeared completely sound and coherent. A few nodules were present on the surface of the plate but the plate appeared suitable for all but the most critical of decorative uses.

Example 15 Using the same vibratory unit as described in Example 1, a cover plate adapted to fit on top of the vibratory hopper was provided with four depending copper bars A6" x /2 and 5" long, equi-spaced from each other by 3 /2" to form the corners of a hollow cube. Extending down from the cover plate and centrally positioned in the hollow cube formed by the anode bars was a cathode rod threaded at the lower end. A round brass doorknob 2%" in diameter by 2" high was threaded to the end of the cathode rod so as to be spaced in the center of such hollow cube. The relationship of the knob to the container was such that the base of the knob was about A" above the bottom of the container. The electrolyte was the copper sulfate-brightener solution described in Example 4. Added to this solution, in the ratio of 6,000 ml. particles to 1,500 ml. solution, the activating media was burning.

30 mesh sintered bauxite particles (XM-30). Vibration at the rate of 2,100 cycles per minute was imposed on the container and plating was carried out at 750 amperes per square foot producing a bright, sound copper deposit over all contours of the knob.

Example 16 The same apparatus setup and curved brass cathode plate described in Example 13 was used with an inert lead anode comprising a /2" x /2" square plate centered on and spaced 1 from the bottom portion of the curved cathode plate. The plating solution was composed of 38 OZ./ gal. SnSO and 38 oz./ gal. H 8,000 ml. of this solution was mixed with 3,000 ml. of 30 mesh sintered bauxite particles (XM-30). Plating was carried out at room temperature with the hopper being vibrated at 2,100 cycles per minute. In this instance, the upper end of the rod supporting the cathode plate was afiixed to the end of a commercial air-actuated vibratory sanding unit. This supplied a reciprocal movement in a verticle direction of about Ma amplitude and a frequency of 180 cycles per minute. A sound, coherent but dull grey tin deposit was formed on the cathode plate at a current density of 900 amperes per square foot.

Example 17 Using the same equipment, electrode and auxiliary vibration set-up of the preceding example, a zinc plating solution was substituted for the tin bath of such example. The zinc solution was composed of 50 oz./gal. ZnSO 9.5 oz./gal. Na SO and 0.8 02/ gal. M-gSO -7H O. Using the same XM-30 particles in the ratio of Example 16, plating was carried out at a temperature held between 130 and 142 F. Semi-bright, coherent, dense and unburned plate was formed at a current density of 360 amperes per square foot. A similar result was obtained by substituting 30 mesh glass spheres as the activating media.

Example 18 Again, using the same arrangement as in Example 1.3 but substituting as the plating solution a used photographic fixer solution (Kodak Rapid Liquid Fix) which had a clearing time of 1.5 minutes, and using 30 mesh glass spheres in the ratio of 8,000 ml. particles to 3,000 ml. of solution, plating was carried out with the same vibratory rate as in Example 13 and at room temperature. The current density was amperes per square foot and produced a compact, semi-bright metallic silver deposit on the cathode plate. Operating under the same conditions in the absence of the activating particles pro- 12 duced no metallic deposit whatsoever at this current (b) establishing a mass rotational movement of said density but rather dull, powdery silver sulfide only. particles in one direction within-said electrolyte and It should be noted that in all of the above examples imparting a microorbiting motion to such particles using the type of equipment described in Example 1 moving in said mass rotational movement, the numthat the amplitude of the vibration was in all such inher of particles immediately adjacent said surface stances prior to such movement being within about 5% of I claim: the number of particles adjacent such surface after 1. An electrodeposition process for plating metal on establishment of such movement; and I I 1, the surface of a part which comprises: (0) contacting the metal deposit on said surface (a) providing in a container for an electro-deposition throughout the entire electrodeposition reaction with system a mixture of fluid eelctrolyte and a plurality said moving particles to mechanically activate said of small, dynamically hard activating particles; deposit as it forms thereon. (b) imposing a vibratory motion at a frequency of at least 500 cycles per minute on said container and References Cited 7 said mixture while said mixture is in contact With all UNITED STATES PATENTS-2M?" surfaces to be plated of said part; l (c) maintaining said vibratory motion throughout the g g g 2/1970 Hewms 204*DIG 10 entire electrodeposition reaction and repetitively con- 7 1965 Maker et 204 DIG' 10 1721949 7/1929 Edelman 204-DIG 10 tactmg said surfaces at extremely short time lnter- 1,051,556 1/1913v Consigllere 204DIG 10 vals by said particles so as to mechanically activate 1 594 509 8/1926 R osenquist 204DIG 10 such surfaces, the number of said particles bemg 3152971 10/1969 T Om oszewski et a1 s sufficiently greatlthat the nclllmber of particles in the space immediate y surroun ing sai surfaces during 7 the imposition of said vibratory motion does not 1214272 71/1917 Bugbe? Ti differ by more than 5% from the number of particles FOREIGN PATENTS lmnotsigih space in the absence of such vibratory 1,500,269 9/1967 France 204 DIG. 10

2. A process as in claim 1 wherein the container is vibrated with an amplitude of vibration of from A to OTHER REFERENCES a Industrial & Eng. Chem, vol. 61, No. 10, October,

3. An electrodeposition process for depositing metal 1969 9-17 on a Surface which comprises: JOHN H. MACK Primary Examiner (a) providing in an electrodeposition system a mixture of fluid electrolyte and a plurality of small, dynami- Assistant Examiner cally hard activating particles which completely covers said surface in the absence of any motion of said particles; 20436, 222, DIG l0 UNITED STATES PATENT oFFIcE CERTIFICATE OF CORRECTEON Patent No. 3, 99,014 Datd Detober 17, 1972 (g) Steve Eisner It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

:Col. 6, line 38, "5H should read SE 0 Col. 11, claim l, line 10, "electro-deposition" should read electrodeposition Col. 11, claim' 1, line 11, "eelctrolyte" should read electrolyte Signed and sealed this 8th day of October 1974.

(SEAL) Attest:

McCOY M. GIBSON JR. C. MARSHALL D'ANN v Attesting Officer Commissioner of Patents F ORM PC4050 (10-69) USCOMM-DC 60376-P69 1*: us. GOVERNMENT PRINTING OFFICE: 1969 o-ses-su

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